Amperometry is used to determine which physiologic parameter?

Amperometry is used to determine which physiologic parameter?

• A. pH
• B. pCO2
• C. pO2
• D. Sodium

Answer: (C)

Amperometry measures current produced by a redox reaction at an electrode, and that current is proportional to the concentration of the electroactive species in the sample. In physiology, the classic amperometric oxygen sensor (Clark-type) reduces dissolved oxygen at the cathode; the resulting current is directly proportional to the dissolved O2, i.e., to pO2. That makes pO2 the parameter determined by amperometry. pH is read by a potentiometric glass electrode that measures hydrogen ion activity, sodium is measured with an ion-selective electrode, and pCO2 is typically determined with sensors that relate CO2 to pH changes or use gas diffusion methods—not the same amperometric oxygen sensor concept.

Amperometry measures current produced by a redox reaction at an electrode, and that current is proportional to the concentration of the electroactive species in the sample. In physiology, the classic amperometric oxygen sensor (Clark-type) reduces dissolved oxygen at the cathode; the resulting current is directly proportional to the dissolved O2, i.e., to pO2. That makes pO2 the parameter determined by amperometry. pH is read by a potentiometric glass electrode that measures hydrogen ion activity, sodium is measured with an ion-selective electrode, and pCO2 is typically determined with sensors that relate CO2 to pH changes or use gas diffusion methods—not the same amperometric oxygen sensor concept.